Variable load brake



March 21, 1944. E. E. HEWITT 1 2,344,868

VARIABLE LOAD BRAKE Filed Jan. 51, 1942 s Shets-Sheet 1 '1 m. IIIIF" INVENTOR ELLIS E.HEWITT Myw a-02m I0 ATTORNEY March 21, 1944.

E. E. HEWITT VARIABLEVIJOAD BRAKE Filed Jan. 51, 1942 3 Sheets-Sheet 2 INVENTOR ELLIS E. HEWIT T GJQCIIM ATTORNEY Wm N wwN NDN m Mm 5 OD @WN *lww 60m 02 0mm owm mm 9m E 1 80M NW D? Patented Mar. 21, 1944 UNITED STATES PATENT OFFICE VARIABLE LOAD BRAKE Application January 31, 1942, Serial No. 429,034

27 Claims.

This invention relates to fluid pressure brakes for vehicles, and more particularly to a brake apparatus adapted to vary the braking power according to the load on the vehicle.

The principal object of my invention is to provide an improved vehicle variable load brake apparatus having means operative upon some necessary operation which must be performed periodically such, for instance, as opening a door of the vehicle, for varying the pressure of fluid obtainable in the brake cylinder according to the load carried.

Another object of my invention is to provide an improved vehicle variable load brake apparatus having means automatically adjustable according to the load on the Vehicle and operative upon the opening of the vehicle door for controlling the pressure of fluid obtainable in the brake cylinder.

A further object of the invention is to provide a vehicle fluid pressure brake equipment which is capable of producing a plurality of different brake cylinder pressures and which is adapted to be automatically conditioned to produce the proper brake cylinder pressure suitable for the vehicle in accordance with the load carried by the vehicle.

Other objects and advantages will appear in the following more detailed description of the invention.

In the accompanying drawings Fig. l is a diagrammatic view, partly in section, of a fluid pressure brake equipment embodying the invention.

Fig. 2 is a fragmentary diagrammatic view, partly in section, illustrating another form of brake equipment embodying my invention.

Fig. 3 is a fragmentary diagrammatic view, partly in section, illustrating another form of equipment embodying the invention.

Fig. 4 is a fragmentary end elevational view of a portion of Fig. 2.

Description of embodiment shown in Fig. 1

Referring to Fig. 1 the variable load brake apparatus may comprise, as shown, a brake controlling valve device I, a brake pipe 2, an auxiliary reservoir 3, a supply reservoir 4, a variable load brake controlling mechanism 5 comprising a valve device having a regulation portion 6 and a relay valve portion 1, a brake cylinder 8, a storage reservoir 9, a pair of magnet valve devices 10 and II and a source of electrical energy which, as illustrated in the present embodiment of the The brake controlling, valve device I is what is known as the D-22 type and may be of substantially the same construction as the corresponding control valve device shown and described in detail in Patent No. 2,152,257 of Ellis E. Hewitt and Donald L. McNeal, issued March 28, 1939. For simplicity in showing the emergency reservoir, the displacement volume device and the straight air pipe all of which are usually associated with and connected to this type of control valve device have been omitted since they are not necessary to a clear understanding of the present invention.

The brake controlling valve device I is employed for the purpose of controlling the application and release of the brakes, and to effect such control is operative upon a service reduction in brake pipe pressure to supply fluid under pressure from the auxiliary reservoir 3 to the relay valve portion 1 of the variable load brake controlling mechanism 5 and is operative to vent fluid under pressure from the relay valve portion in response to an increase in brake pipe pressure. The supply of fluid under pressure to and the release from the relay valve portion is by way of a pipe [2 which connects said valve portion to the brake controlling valve device I. The relay valve portion of the variable load brake controlling mechanism is operative in response to the pressure of fluid supplied thereto and the venting of fluid therefrom, as will hereinafter be more fully described. 2

The variable load brake controlling valve device 5 is provided for the purpose of controlling the supply of fluid under pressure to and the release of fluid under pressure from the brake cylinder 8, the supply in the present embodiment of the invention being from the normally charged reservoir 9 and the, release being to the atmosphere. This device as hereinbefore mentioned comprises a regulating or changeover portion 6 and a relay valve portion 1. V V V The relay valve portion I shown in the draw ings may be the same general type as that shown and described in Patent No. 2,236,268 O E. E. Hewitt, issued March 25, 1941, assigned to the assignee of the present application and may be briefly described as comprising a casing in which there is operatively mounted a fluidpressure supply and release valve mechanism, not shown. and a difierential diaphragm assemblage which is operative'to efiect the operation of the valve mechanism. I The supply and release valve mechanism isof the self-lapping type comprising a invention is in the form of a storage battery I3. supply valve and a release valve for controlling respectively the supply of fluid under pressure from the storage reservoir 9 to the brake cylinder 8 and the release of fluid under pressure from the brake cylinder.

The difierential diaphragm assemblage for operating the valve mechanism comprises a series of movable abutments in the form of flexible diaphragms I5, I6, I1, and 58 of successively smaller effective pressure areas. in the order named, the diaphragms being suitably clamped at the periphery thereof by the casing and disposed in spaced coaxial relation.

At one side of the largest diaphragm I5 is a.

follower plate or disc 26 which is operatively connected to a plunger, not shown, for effecting operation of the self-lapping valve mechanism and suitably attached to the opposite side of this diaphragm is a follower member 2I. The diaphragms I5, I6, I1 and I8 are operatively associated with each other and are maintained spaced apart by means, of spacers or follower members 22, 23, and 24, which are disposed between the diaphragms I5 and I6, I6 and Ill and I 1 and I8, respectively. It will be noted that the diaphragms are not positively connected together so that they are free to move individually or collectively, as the case mightbeto control the selflapping valve mechanism. 1

One surface of the diaphragm I5 and the inner surface of the casing defines a chamber 25 in which the self-lapping valve mechanism is lo-'- cated; the adjacent faces of the diaphragms I5 and I6 and an inner surface of the casing defines a chamber 26; the adjacent faces of the diaphragms I6 and I7 and an inner surface of the casing defines a chamber 21; the adjacent faces of the diaphragms I! and I8'and an inner surface of the casing defines a chamber 28 and the other surface of the diaphragm I8 and an inner surface of the casing defines a chamber 30.

Contained in chamber 30 is a bias spring 3I which acts through a plate 29 against the adjacent face of the diaphragm I8, said plate being supported in coaxial relation with said diaphragm on a boss 33' projecting from the adjacent face of the diaphragm. The outer end of the spring is supported in a cap nut 34 having. screw-threaded engagement with the casing and is employed to hold the several diaphragms and the followers interposed between, in engagement with each other to avoid rattling or shaking of the parts when the brakes on the vehicle are released. The chamber 35 is constantly connected to the pipe I2 leading to the brake controlling valvev device I through a passage 32.

Interposed between the chambers 26, 2I and 28 and the passage 32 are check valves 35, 35a and 35b, respectively, which are yieldingly biased into seated relation on an associated valve seat by lightly tensioned return springs 36 Whenever a reduction in the pressure of the fluid in the passage 32 occurs, as a result of a reduction in the pressure of the fluid in the pipe I2, the check valve 35, 35a and 35b are unseated by the higher pressure in chambers 26, 2! and 28 to cause substantially simultaneous reduction, to a corresponding degree, in the pressure of the fluid con-' tained in the chambers 26, 21, and 28. The purpose of this feature will be understood more clearly from subsequent description.-

The regulating or changeover portion 6 of the variable load brake controlling mechanism 5 is provided for the purpose of selectively cutting. the chambers 26, 21, and 28into communication iii with the pipe I2 and is operative according to the load on the vehicle to its several selecting positions. This portion of the valve device may comprise a casing containing a piston 38 having a piston rod or stem 39 which extends to the exterior of the casing. At one side of piston 38 is a chamber 3! which is in constant open communication with a passage and pipe 40 leading to the magnet valve device I6. At the opposite side of the piston is a chamber II which is in constant open communication through a passage 42 with the atmosphere.

Contained in chamber ll and interposed between and operatively engaging the piston 38 and the casing is a spring 63 which tends, at all times, to move said piston to its extreme left hand or empty vehicle position, as shown in Fig.

1 of the drawings.

The outer end of the piston rod or stem 39 is pivotally connected to a lever M by means of a pin 45 which passes through the lever at a point between the ends of the lever. One end of the lever 4 is pivotally connected to one end of a link 46, which link at its opposite end, is connected to a longitudinally movable ratchet bar 41. The other end of lever 64 is connected, by means of an adjusting lever extension 48 and a link 39, with a rod 56, which rod in turn is pivotally connected at its outer end with one arm of a bell crank 5i, carried by the vehicle body. A member 52 carried by the car truck is positioned to be engaged by a roller 53 carried by the outer end of the other arm of the bell crank SI.

The ratchet bar 4! is slidably mounted in the casing for longitudinal movement and is arranged to operate a selector slide valve 54 contained in a chamber 55, which chamber is constantly connected by way of a passage 56 with the atmosphere. its inner end with an extension 51 which is slidably guided and supported in the casing. This eX- tension extends into a bore 58 and within the bore is provided with a collar 60. The open end of this bore is closed by a nut 59 having screw-threaded engagement with the casing. Contained in the bore 58 and interposed between and operatively engaging the collar and the inner end of the bore is a spring 6| which tends, at all times, to urge the ratchet bar in a direction toward the left hand into the position in which it is shown in Fig. 1 of the drawings.

The ratchet bar is also provided with teeth 62 which are adapted to be engaged by a pawl 63. This pawl is connected to a piston 64, subject on one side to the pressure of a spring 65 and subject on the opposite side to the pressure of fluid in a piston chamber 66. which is connected to the magnet valve device II by way of a passage and pipe 61.

The magnet valve device it? comprises a pair of oppositely seating valves, '56 and H, which are yieldingly urged by a spring 52 into seated and unseated positions, respectively, and which are actuated against the force of the spring I2 into unseated and seated positions, respectively, upon energi'zation of an electromagnet I5. With the valve II unseated as shown communication is established from pipe and passage lil connected to chamber 3?, to ah atmospheric passage 76, this communication being closed when the valve II is seated. When the valve i9 is unseated communication is established from the supply reservoir 4 to the pipe 45 by way of pipes El, and 13, a cham- The ratchet bar is provided at' ber 19 in the magnet valve device, past unseated valve I8 and a chamber 88 to charge the chamber 31 with fluid under pressure this communication being closed when the valve I8 is seated.

The magnet valve device I I is identical in construction to the magnet valve device I8 and comprises a pair of oppositely seating valves, GI and 82, which are yieldingly urged into seated and unseated positions respectively by a spring 83 and actuated against the force of the spring 83 into unseated and seated positions, respectively, upon energization of an electromagnet 84. With the valve 82 unseated, as shown, communication is established from the supply reservoir 4 to the pipe 61, so that fluid under pressure in supply reservoir 4 flows to the piston chamber 63 to charge it, by way of pipes 11 and I8, a chamber 85 in the magnet valve device II, past unseated valve 82 and a chamber 85, this communication being closed when the valve 82 is seated. With the valve BI unseated, communication is established from the pipe and passage 81 leading from chamber 65, to the atmospheric passage 81, this communication being closed when the valve BI is seated.

The electric circuit for controlling the operation of the electromagnets I5 and 84 is of the normally open type which is controlled by operation of the vehicle doors. One end of the coil or winding of the electromagnet i5 is connected to the positive terminal of the storage battery I3 by means of a conductor 93 and the other end of the coil or Winding is connected to one end of the coil or winding of the electro-magnet 84 by means of a conductor 94. The other end of the coil or winding of electro-magnet 84 is connected to one terminal of each of a plurality of door switches 9| by means of a conductor 85 and connected con-. ductors 96 and 9?. The other terminal of each of the door switches is connected to the negative terminal of the storage battery I3 by means 0 connected conductors 98, 99 and I88.

Operation of embodiment shownin Fig. 1

In initially charging the brake system fluid under pressure supplied to the brake pipe in the usual manner flows to the auxiliary reservoir by way of the brake controlling valve device I and a pipe I8I. Fluid under pressure also flows from the brake pipe by way of the brake controlling valve device I to pipe I8 and therefrom through pipe 1'! to the supply reservoir 4. Fluid under pressure also flows from the pipe I8 to the chambers I9 and 85 of the magnet valve devices I8 and I I, respectively.

" The storage reservoir 3 which is provided for the purpose of storing fluid under pressure to be supplied to the brake cylinder may be charged directly from a suitable fluid pressure supply source, such as a compressor or main reservoir by Way of a pipe I82. Fluid under pressure thus supplied to reservoir 3 flows therefrom to the usual supply chamber of the relay valve portion I of the variable load brake control mechanism 5 through a pipe I83, from whence fluid under pressure is supplied to the brake cylinder 8upon operation of the valve mechanism to application position as hereinafter described.

When a vehicle equipped with the above described variable load brake equipment is charged with fluid under pressure and is running along the road empty with all the car doors 92 closed, as shown in full lines in Fig. 1, the switches 9| will be open, so that the electro-magnets I5 and 84 will be deenergized. With the electro-magnets-.'I5 and 84 deenergized, the double beat valves I8 and II of magnet valve device I8 and the double beat valves BI and 82 of the magnet valve II will be in the position shown in Fig. 1 of the drawings.

With the double beat valves I8 and I I positioned as shown the chamber 31 in the variable load control mechanism is open to the atmosphere, by way of passage and pipe 48, past unseated valve II and through atmospheric passage I8. From this it is obvious that there will be no fluid pressure acting on piston 38 so that the spring 43 acts to maintain the piston 33 in its extreme left hand position as shown in Fig. 1. With the piston and attached piston rod or stem 39 and consequently the lever 44 thus positioned, the bell crank 5| at the outer end of the attached rod 58 will be in the position shown so that the free arm thereof will maintain the roller 53 away from or out of contact with the member 52, so that the usual relative movement between the truck and the vehicle body, while the vehicle is in motion, will have no effect upon the bell crank thus preventing the transmission of damaging forces to the bell crank and associated parts.

Under these conditions the spring 6| acting through the collar 68 and extension 51 will maintain the ratchet bar 41 and selector slide valve 54 in the position shown in the drawings. With the selector slide valve 54 thus positioned the chambers 26, 21 and 28 of the relay portion I are connected to the atmosphere by way of passages I86, I and I84, respectively, chamber 55 and atmospheric passage 56. As hereinbefore mentioned the chamber 38 is in constant open communication with passage 32 and pipe I2, which pipe is connected to the atmosphere through the brake controlling valve device I, in the usual manner, when said valve device is in brake release position.

Since the diaphragm chambers 26, 21, 28, and 38 are all connected to the atmosphere as just described the self-lapping valve mechanism contained in the relay valve portion I is maintained in its release position thus connecting the brake cylinder 8 to the atmosphere to maintain the brakes on the vehicle released.

With the double beat valve BI and 82 positioned as shown communication is established for supplying fluid under pressure from the supply reservoir 4 and connected pipe I8 through pipe and passage 61 to the piston chamber 66. Upon the supply of fluid under pressure to chamber 88 the piston 64 is moved upwardly against the opposing pressure of th spring 65 to hold the pawl 63 in engagement with the teeth 62 of the bar 41, thereby locking the ratchet bar 41 and selector slide valve 54 in the position shown.

Application of the brakes on an empty vehicle When the brake pipe pressure is reduced to effect an application of the brakes the brake controlling valve device I functions in the usual well known manner to supply fluid under pressure from the auxiliary reservoir 3 to diaphragm chamber 38 of the relay valve portion I by way of pipe I2 and passage 32, the flow of fluid from the auxiliary reservoir to the brake controlling valve device being by way of pipe I8I. Fluid under pressure supplied to chamber 38 causes the diaphragm assemblage to function to actuate the valve mechanism to first seat the exhaust valve and to then unseat the supply valve. With the supply and exhaust valve thus positioned/fluid under pressure flows from the storage reservoir 9 through pipe I03 to the chamber 25' and from thence to the brake cylinder 8by way of apipe I01. When the pressure of fluid in chamber 25 and acting on diaphragm l5 becomes high enough to overcome the opposing pressure of fluid in chamber' 30 acting on the diaphragm lathe diaphragm assemblage will be shifted in a direction toward the right. hand, permitting the supply valve to seat thereby cutting ofi further flow of fluid under. pressure tochamber 25'. With the flow of fluidv thus cutoff there will be no further increase in the pressure in chamber. 25, consequentl the diaphragm assemblage will come to astop before. the release valve can be unseated. When this occurs the brakes. will be. maintained applied with a pressure called for by the relay valve portion;

From. the foregoing it will be apparent that with only the diaphragm chamber 35 charged with fluid under pressure the pressure established in the brake cylinder 8 is determined by the relation of the effective pressure area of the diaphragm l8 to the effective pressure area of the diaphragm 15, thus the pressure established in the brake cylinder will be proportionate to the pressure established in pipe i2 and. connected chamber 30 when the vehicle is empty.

Now when the brake pipe pressure is increased to-efiect a release of the brakes the brake controlling valve device I will. function to establish communication from the pipe i2 to the atmos pheresothat fluidunder pressure will lee-vented from chamber 30. With the chamber 30-thus vented the fluid at brake cylinder pressure present in. chamber 25 and acting on the diaphragm l5 will cause. the diaphragm assemblage to move further in a. direction toward the right hand. I

Upon such movement the self-lapping valve mechanism will operate to unseat the exhaust valve and thereby permit fluid under pressure to flow from the brake cylinder by way of pipe It? to. the atmosphere, thus releasing the brakes.

When the vehicle is brought toa stop and one or more of the. vehicle doors. 92 are opened as shown in dotted lines in Fig. 1, the circuit of electro-magnets l5 and. 84 will be closed through the switches 9|. The. energization of electromagnet 84 seats the valve 82 and unseats the valve 8|. With the valve 8! unseated, fluid under pressure in the piston chamber 66 of the variable load brake controlling mechanism 5 will be vent.- ed to the atmosphere through passage and pipe '61, chamber. 88' in the magnets valve-device. H, past unseated valve Si and through atmospheric exhaust passage 87. The reduction of fluid pres.-v

sure in chamber 655 permits the spring to force the piston 54' downwardly drawing the. pawl 53 out of locking engagement with a tooth 62' of the ratchet bar 41'.

The energization of electro-magnet seats the valve H and unseats' the valve It, and thefluid under. pressure in the supply reservoir 4.. is permitted to flow to the chamber 37 of the regulating. portion of variable load brake controlling mechanism 5, by Way of pipe Ti and. I8, chamber i the magnet valve device It, past unseated valve 10, chamber 88 andpipe 46. a

Fluid under. pressure supplied to chamber 31 causes the piston 38 and attached piston. mess to 'move outwardly against the opposing pressure of spring 43. causes the lever 44. to rock in a clockwise directionabout a pin l 50,,which. pin at this time is maintained stationary by the link. 46- and' connected bar 41 which in turn is held: stationary. by the spring 6 I. r

The piston rod as it thus moves The lever 44- as it is thus: rocked causes the rod. 50 to: move longitudinally in the direction toward. the. right hand, the rod as it-moves imparting a clockwise.- rotary movement to the bell crank. 5| about pivot pin HI until. such movement isstopped. by the engagement of the bell crank. roller 53 with the fixed part 52 of the truck. It will: here be understood that since the vehicle: is empty the. piston 38 will have made its full traverse at. the time the roller 53 engages with. the fixed part 52 of the truck so that; even. though. they locking pawl 63 is in. its unlocked. position the .bar 41 and associated slide valve 54 will not be caused to move from their empty position.

Now as the vehicle is loaded the vehicle body will move downwardly, due to the compression ofthe body supporting springs by the increasing load, relative to the fixed part. 52 of the vehicle truck. The bell crank since it is carried by the vehicle body and isin operative engagement with the fixed part 52 of the truck is carried to rock in a counterclockwise direction about its pivot. in response to the downward movement of the vehicle .body. The bell crank as it thus moves causes. the rod 50 to be moved longitudinally in a direction toward the left hand, the bar in its movementshifting the connected end of the lever 44 in the same direction. Since the piston 38 and piston rod 39 are in their extreme right hand position the lever 44, due to its movement by the rod 50, will rock in a. counterclockwise direction about the pin 45. This movement of the lever 44 will continue as long as the load on the vehicle is being increased until the vehicle is fully loaded.

The lever 44 as it rocks in response to the increasing load on the vehicle pulls the bar 41 longitudinally and consequently the slide. valve 54 toward the right hand. against the opposing pressure of the spring 4|, the. slide valve 44 assuming any one of. its three load positions depending upon the degree of increase of the load. When the vehicle has been loaded, the vehicle 1 doors are closed, the doors as they move from their open position, opening the. circuit through the switches 9| and electro-magnets l5 and 84 thus. efiecting the deenergization of electro-magnets 75 and 84.

With. the electro-magnet 34 deenergized, the spring 83 acts to unseat the valve. 82 and to seat valve 8|. With the valve 82 unseated,. fluid under pressure from the supply reservoir 4 is again supplied to the piston chamber 66 through the circuit hereinbefore traced; When the pressure of fluid in piston chamber 66 has been increased to a degree sufficient to overcome the opposing pressure of spring 65, the piston is move upwardly causing the pawl 63' to engage one of the teeth of the ratchet bar 41, thus locking the ratchet bar and attached selector slide valve 54 in the proper adjusted position.

When the-electro-magnet l5is deenergized the spring 14 acts to seat valve 10 and to unseat valve 1|. With the valve H unseated, chamber 31 of'the regulating portion 6 is vented to theatmosphere through a circuit previously traced in the foregoing description. The reduction of the pressure of fluid in chamber 3! due to such venting. permits the spring 43 to force the piston and attached piston rod 39 to the leftto its retracted position thereby causing the lever 44 to rotate in a counter-clockwise direction about the now stationary pivot pin H0; The; lever 44zas1itlsthus moved causes the rod 50 to move in a direction toward the left, thus rocking the .bellcrank 5I in a clockwise direction about the pivot pin HI so that the roller 53 is moved out of engagement with the member 52, for the purpose hereinbefore described.

As hereinbefore mentioned the selector slide valve 54 will be positioned according to the load on the vehicle. If the vehicle is fully loaded the slide valve will assume its full load position in which a branch passage 32a, leading from the passage 32, is connected by way of a cavity I I5 in the slide valve 54 to the passages I05, I05, and I04 leading to the diaphragm chamber 25, 21, and 28, respectively. If the vehicle is only lightly loaded the slide valve will be positioned so that the cavity I15 therein will connect the passage 32a to the passage I04, and if the vehicle is more heavily loaded, but not fully loaded, the slidevalve will be'positioned so that the cavity II5 will connect the passage 32a to the passage I04 and I05.

When it is desired to eifect an application of the brakes, fluid under pressure from the brake controlling valve device I will be supplied through pipe I2 and passage 32 to chamber 30 f the relay valve portion I as hereinbefore described in connection with an application of the brakes on an empty vehicle. As above described the selector slide valve 54 will be positioned according to the load on the vehicle, thus if the vehicle is fully loaded fluid under pressure supplied to passage 32 will also flow by way of passage 32a, cavity H in side valve 54 and passages I06, I05, and I04 to chamber 26, 21, and 23, respectively.

It will thus be seen that all of the chambers 26, 21, 28 and 30 are charged with fluid under pressure from the passage 32 and, consequently, that the fluid pressure forces acting on opposite sides of the diaphragms I5, I1, and I8 are balanced, the largest diaphragm I 5 alone being subject to the unbalanced force of fluid under pressure acting in chamber 25 on the right hand face thereof. Under these conditions the diaphragm I5 is accordingly flexed individually to effect the operation of the self-lapping valve mechanism while the remaining diaphragms remain stationary. Under these conditions a high brake cylinder pressure is obtained for any given increase in the pressure of fluid in pipe I2.

If the vehicl is empty the slide valve 54 will be in the position in which it is shown in Fig. 1 so that when an application of the brakes is initiated the supply of fluid under pressure to the brake cylinder will be under the control of the smallest flexible diaphragm I8, so that a light I brake cylinder pressure is obtained for any given increase in the pressure of fluid in pipe I2. If however the vehicle is lightly loaded the slide valve 54 will be in the position in which it establishes communication from the passage 32a to' the passage I54 and diaphragm chamber 28, so that the diaphragm H which has a greater face area than the smallest diaphragm I8 acts to control' the valve mechanism to provide a higher brake cylinder pressure for any given increase higher brake cylinder pressure for any given increase in the pressure of fluid in pipe I2.

In initiating the release of the brakes after an application effected on a fully loaded, or a partially loaded vehicle, fluid under pressure in the pipe I2 is vented to the atmosphere by the brake controlling valve device I as previously described in connection with a release of the brakes after an application on an empty vehicle. In the event of a fully loaded vehicle fluid under pressure in chambers 20, 21, and 28 is vented to the atmosphere pastthe check valve 35, a and 35b, respectively and also by way of passage I06, I05, and I04 respectively, cavity I I5 in the slide valve 54, passage 32a, passage 32' and pipe I2. The chamber 30. being directly connected to the passage 32 obviously reduces with the pressure in pipe I2 independently of the check valves 35, 35a and 3511.

When the vehicle is partially loaded the pressure in any of the chambers 21 and 28, which is charged with fluid under pressure, is correspondingly and rapidly reduced according to the reduction in pressure in pipe I2, by flow of fluid past check valve 35a and 35b, respectively and also by way of passage I05 and I04, respectively, cavity H5 in the slide valve 54, passage 32a and passage 32'. As before mentioned in connection with release on a fully loaded vehicle the pressure of fluid in chamber 30 reduces independently of the check valves and also independently of the slide valve 54.

With these chambers vented, fluid under pressure in chamber 25 will cause the diaphragm assembly to move to its release position in which it is shown in Fig. 1 of the drawings to cause the exhaust valve of the self-lapping valve mechanism to be unseated thus venting fluid under pressure from the brake cylinder tothe atmosphere to effect a release of the brakes,

It will be understood from the foregoing description that in empty vehicle braking for a chosen pressure of fluid supplied to pipe I2 a lighter brake application will be obtained than when the vehicle is either partially or fully loaded. It will also be understood that when the vehicle is fully loaded a heavier brake application will be obtained than when it is partially loaded. All of this is due to the action of the-differential diaphragms I5, I6, I1, and I8 and to their selection by the adjusting or change over portion I of the variable load control valve device 5 in accordance with the load on the vehicle.

If at any time while the vehicle doors are open, the load on the vehicle is decreased, the body of the vehicle will move upwardly, due to the action of the body supporting springs, relative to the fixed member 52 0f the truck. When this occurs the spring GI in the variable load mechanism 5 acting through the medium of the collar 00 and bar extension 51 moves the bar 41 and consequently the slide valve 54 in a direction toward the left hand to the proper adjusted position in accordance with the reduction in load on the vehicle.

Description of the embodiment shown in Fig. 2

In Fig. 2 of the drawings another form of the invention is illustrated in which the control of the supply of fluid under pressure to and the release of fluid under pressure from the relay valve portion is accomplished through the medium of electrical means operative according to variations in the weight of the load carried by the vehicle.

As shown this form of thevariable load mechanism comprises a relay valve device I50, a regulating device II, comprising a valve gportion I52 and electric switch portion I53, for controlling the relay valve device and a fluid pressure motor I54 for positioning the regulating device.

It will be understood that this variable load mechanism is employed with the brake controlling valve device I, the brake cy1inder-8 the storage reservoir 9 and the switches 9| associated with the vehicle doors- 92, shown in .Fig. 1.

,As shown the relay valve device I50 comprises a difierential diaphragm assemblage identical with that shown in the relay portion 1, of the variable load mechanism '5 associated with Fig. 1, which diaphragm ,portion is operative'in the same manner to control the operation of a supply and release valve mechanism, not shown, but described in connection with the equipment illustrated in Fig. 1. .In addition, this relay valve deviceis provided with a magnet valve casing section I58 containing .magnet valve devices I51, I 58, and I59 which serve to control the supply of fluid under pressure to and the release of fluid under pressure from the chambers 28, 21, and 26, respectively.

The magnet valve device I51 comprises apair of oppositely seating valves I50 and IBI, which are yieldingly urged by a biasing spring I61 into seated and unseated positions, respectively, and which are actuated against the force .of the spring I81 into unseated and seated positions, respectively, by energization of an electromagnet I68. The valve I68 .is contained .in ,a chamber I89 which .is in constant .open communication with passage .32 by way of a passage I10.

The valve IBI is contained in achamber .I1I

which is constantly open to the atmosphere through an exhaust passage 112.

Located between. the chamber I-692and |1I| is a chamber I13 which is constantly connected to passage I04 and connected diaphragm chamber 28.

It will thus be seen that when the electromagnet M58 is .deenergized, as shown, the valves I88 and IN are seated and unseated, respectively. With the valves thus positioned the valve I68 cuts off the supply of'fluid under pressure .from chamber I69 and consequently connected passages I10 and .32 to chamber I13, and the chamber I13 is vented to the atmosphere through passage I12 past the unseated valve 161. When the electromagnet IE8 is energized, the valve I GI is seated to prevent exhaust of fluid under pressure from chamber I713 and the valve I50 is unseated to permit fluid under pressure to flow from chamber I89 to chamber I13 and connected passage I04.

The magnet valve device I58 is identical in construction with magnet valve device I51 and comprises a valve I14 and a valve I15, yieldingly urged into seated and unseated positions, re-

spectively, by a biasing spring I15 and actuated against the force of the spring I16 into unseated and seated'positions, respectively, by energization of an electromagnet I11. The valve I14 is contained in a chamber I18 constantly connected to passage .32 by way of passage I10, and the valve I15 is containedin a chamber I13 which is constantly open to the atmosphere through the exhaust passage I12.

Located between the chambers I18 and I99 is a chamber I88 which is constantly connected to the diaphragm chamber 21 by way of passage I05.

When the electromagnet I1] is deenergized the valve I14 is seated to close off the supply of fluid under pressure :from the chamber I18 to the chamber I and the valve I 15 is unseated to release .fiuid under pressurefrom chamber I80 to chamber I19. When the electromagnet I11 is energized, the valve I15 .is seated to close off the flow of fluid under pressure from .the chamber I80 to the chamber I 19 and the valve I14 is unseated to permit fluid under pressure to be supplied .from chamber I18 to the chamber I80.

The magnet valve device I59 is identical in construction with the magnet I58 and comprises a valve I84 and a valve I85, y e y urged into seated and unseated positions, respectively, by a biasing spring I86 and actuated against the force of spring I88 into unseated and-seated positions, respectively, by energization of an electro-magnet I81. The valve I84 :is contained in a chamber I88-constantly connected to passage I18, and the valve I is containedina chamber I89 which is constantly open to the atmosphere by way of exhaust passage I12.

Located between the chambers I88 and I89 is a chamber I99 which is constantly connected to the diaphragm chamber 26 by way of passage I95.

When the electromagnet I81 deenergizecl the valve I84 is seated to close off the supply of fluid under pressure from chamber I88 to the chamber I90 and the valve I85 is unseated to release of fluid under pressure from chamber I90 to chamber I89. When the electro-magnet I81 is energized, the valve I85 is seated to prevent the flow of fluid under pressure from the chamber I98 to the chamber I89 and the valve I84 is unseated to permit .fluid under pressure to now from chamber I88 to the-chamber I98.

The magnet valve casing section I58 of the relay valve device I50 is arranged to carry a fluid pressure responsive switch device I9I which as shown may comprise a casing containing a piston I92 having a stem I93 on which is carried, in insulated relation, a contact bridging member I94 for connecting, in circuit-closing relation, a pair of fixed contact members I95, one of which is connected to the positive terminal of a storage battery I3 by means of a conductor I98 and the other of which is connected to a conductor I91 leading toa contact finger .or member I98 contained in the adjusting portion I53 of the variable load mechanism. .At one side of the piston I92 is a spring I98 which yieldingly urges the piston downwardly into engagement with the end cover of the casing, in which position the contact-bridging member I94 is out of contact with the contact members I so as to maintain open the battery circuit through the contact member I98. At the opposite side of the piston I92 is a chamber I99 which is constantly connected to the passage I18 by way of a branch passage 20!).

Whenever the pressure of fluid supplied to chamber I99 and acting on the piston I92 is sufflcient to overcome the spring I98, the, piston I92 and thereby the contact bridging member I94 are ,shifted'upwardly. The contact bridging member I94 engaging the contact members I95.

The regulating device I5I which is provided for selectively energizing or deenergizing the magnet valve devices I51, I58, and I59 is operated, according to the load on the vehicle, to its several selecting positions. This device as hereinbeiore mentioned may comprise a valve portion I52 and a switch portion I53.

The valve portion I52 as shown comprises a casing containing a piston 20I having a stem 202. At one side of piston MI is a valve chamber 203 containing a slide valve 204 which is arranged to be operated by the stem 202. At the opposite side of the piston is a chamber 205 which is in constant open communication with passages 206 and 201. Contained in chamber 205 is a spring 208 which, at all times, tends to urge the piston 201, piston stem 202, and slide valve 204 downwardly to the position in which they are shown in the drawings.

Leading from the seat for the slide valve 204 are passages 209 and 210, the passage 209 being open to the atmosphere and the passage 210 being open to a pipe 211 connected to the'piston chamber 266 of the fluid pressure motor 154.

For the purpose of controlling the operation of the piston 201 and consequently the slide valve 204 a magnet valve device 215 is provided, which magnet valve device is carried by the casing of the valve portion 152. This magnet valve device comprises a pair of oppositely seating valves, 216 and 211, contained in a chamber 218 which is connected to the passage 206. These valves are yieldingly urged by a spring 219 into seated and unseated positions, respectively, and are arranged to be actuated against the force of the spring 219 into unseated and seated positions, respectively, upon energization of an electro-magnet 220. With the valve 2I1 unseated as shown, communication is established from the supply reservoir 4 to the passage 206, by way of pipe 18, a chamber 221 in the magnet valve device, past unseated valve 211 and chamber 2i 8, the valve 211 when seated closing this communication. With the valve 216 unseated, communication is established from chamber 218 connected to passage 206, to an atmospheric passage 222, the valve 216 when seated closing this communication.

The electric circuit for controlling the operation of the electro-magnet 220 is controlled by operation of the vehicle doors. One end of the coil or winding of this electro-magnet is connected to the positive terminal of the storage battery 13 'by means of conductor 93 the other end of the coil or winding is connected to the conductor 95 which leads to the door switches 91, which switches in turn are connected to the negative terminal of the storage battery 13, by means of conductors in the same manner as shown and described in connection with the equipment shown in Fig. 1 of the drawings.

230, which link at its opposite end is connected to a longitudinally movable ratchet bar 231.

The ratchet bar 231 is slidably mounted in the casing for longitudinal movement and is provided with teeth 232 which are arranged to be engaged by the teeth of a pawl 233. This pawl is connected to a piston 234, subject on one side to the pressure of a spring 235 and subject on the opposite side to the pressure of fluid in a piston chamber 236. which is connected to the passage 201 leading to the chamber 205 in the valve portion 152 of the adjusting device.

The bell crank arm 221 is provided with an extension in the form of a contact arm 231'which is arranged to selectively connect the contact finger or member 198 in circuit-closing relation with a plurality of contact fingers 238, 239 and 75 240. The contact fingers 238, 239, and 240 are connected by conductors 241, 242, and 243, re spectively, to one terminal of the electromagnet windings 168, 111, and 181 of the magnet valves 151, 158, and i59, respectively. The opposite ter minals of the electro-magnet windings 168, 111, and 181 are connected to ground as shown.

Contained in the casing and interposed be tween and operatively engaging one side of the arm 221 and the casing is a spring 244 which tends. at all times, to move the arm 221 and consequently the contact arm 231 to the position in which they are shown in Fig. 2 of the drawings. The roller 229, hereinbefore mentioned, carried at the outer end of the arm'226 engages a cam surface 245 provided on a longitudinally moveable bar 246, which bar is a suitable guide in the casing by means of rollers 241 and 248. This bar is provided with an integral extension 25! which extends through chamber 249 to the exterior of the casing. The extension is slidably guided and supported at its outer end by the casing.

Contained in the chamber 249 and interposed between and operatively engaging a spring seat 250 and the casing is a spring 252 which tends, at all times, to urge the bar 246 in a direction toward the left hand into the position in which it is shown in Fig. 2 of the drawings. seat 250 encircles the extension 25! and is at all times maintained in abutting relationship with the shoulder formed on the bar 246.

The outer end of the extension 251 is pivotally connected to one end of a lever 253 by mean of a pin 254, which lever intermediate its ends is pivotally connected by means of a pin 255 to a bracket 256 carried by the casing of the switch portion 153. The other end of the lever 253 is connected by means of a pin 256 with one end of a rod 251, which rod, at its opposite end is connected to a longitudinal movable rack bar 258.

The bar 258 is slidably mounted in lugs 259, carried by the casing, for longitudinal movement and is provided with teeth 250 which are arranged to mesh with corresponding teeth on a gear wheel 261 which is also carried on the casing by means of a pin 262. The gear wheel 261 is adapted to be driven by a vertically movable rack bar 263 which is slidably mounted in a lug 264 carried by the casing, the bar being provided with teeth which mesh with the teeth of the gear wheel.

The fluid pressure motor 154 for positioning the regulating portion 151 is mounted on a relatively fixed part of the vehicle truck. This motor, as shown, may comprise a cylinder casing containing a piston 265 having a stem or push rod 213 which extends to the exterior of the casing.

At one side of the piston 265 is a chamber 266 which as hereinbefore mentioned, is in constant open communication with the pipe 211. At the opposite side of the piston is a chamber 261 which is connected to the atmosphere by way of a passage 268.

The stem or push rod 213 extends through a bore 269 in a fixed part 210 of the truck. Beyond the part 2? the outer end of the stem is adapted to engage the lower end of the bar 263 carried by the adjusting valve device 15! located on the car body. The stem 213 is provided adjacent the outer wall of the cylinder casing with a spring seat 21!. Interposed between and operatively engaging the spring seat and the fixed part 210 cf the truck is a spring 212 which tends, at all times, to urge the piston 265 and attached stem The spring m P h od to the position. in which they are shown iniFig. 2 of the, drawings.

1' Operation of the equipment shown in Fig. '2

In describing the operation of the embodiment of the invention shown in Fig. 2 it will first be assumed that the vehicle doors are closed, the vehicle is empty, the brakes released and the system being charged with fluid under pressure in the manner hereinbefore described in connection with the equipment shown in Fig. 1.

Under these conditions fluid under pressure flows from pipe I8 to chamber MI in the magnet valve device 2I5 from whence it flows by way of apassage 215 to chamber2il3 at one side of piston ZBI. Since the electro-magnet 220 is deenergized the valves 2 I S and 2 I 1 will be positioned as shown, thus fluid under pressure in chamber 22I flows past unseated valve 2I'I to chambers 2E8 from whence it flows to chamber 205 at the opposite side of the piston 2i by way of passage 286. The fluid pressureacting on opposite side of piston 2M will thus be equal so that the spring 208 acts to maintain said piston and slide valve 284 in the position shown. a

With the slide valve 204 thus positioned the chamber 26$ in the fluid pressure motor IE4 is connected to the atmosphere, by way of pipe 2I I, passage 2H a cavity 216 in the slide valve 204 and passage 2%. With the chamber 258 thus vented to the atmosphere, the spring 212 acts to maintain the piston and push rod 213 in its eX- treme lower position as shown in Fig. 2. With the piston and push rod in this position, the outer end of the push rod will be maintained out of engagement with the end of the bar 263, so that the usual relative vertical movement between the truck and the vehicle body, while the vehicle is in motion, will have no eifect upon the bar 263 and consequently the gear 25I, thus preventing the transmission of damaging forces to the gear 26I and associated parts.

Under these conditions the spring 252 acting through the spring seat 250 maintains the bar 248 in its extreme left hand position as shown, With the bar 246 thus positioned the roller 229 carried by the arm 226 of the bell crank lever 225 is in engagement with the right hand or highest end of the inclined surface of the cam 245, thus permitting spring 244 acting on the arm 22! to maintain the bell crank lever 225 in the position in which it is shown. With the bell crank lever 225 thus positioned, the contact arm 23'! is maintained out of engagement with the contact fingers 233, 239, and 2 53, thus the electro-magnets I68, H7, and I8! of the magnet valves I51, I58, and IE9, respectively, will be maintained deenergized. Since the bell crank lever is maintained in. the position shown the attached rachet bar 23I will be in its extreme left hand position as shown.

When initially charging the equipment, fluid under pressure will be supplied to chamber 285 of the valve portion I52 of the regulating valve device 554 from whence .it will fiowby way of passage 25s! to piston chamber 236.. Fluid. under pressure supplied to chamber 236 causes the piston 23a to move downwardly against the opposing pressure of the spring 235 causing the teeth of the When an application of the brakes is effected in the manner hereinbe'fore described in connection amass-e with Fig. 1, fluidunder pressure is supplied to the diaphragm chamber 3 3 cf'the'relay valve device ifiil by way of pipe .52 passage Fluidunder pressure supplied to chamber causes'the diaphragm assemblage to function to actuate the valve mechanism to supply fluid under pressure to the chamber and connected pipe its leading to the brake cylinder.

From the foregoinr. it will be seen that if the vehicle is empty and an application of the brakes is effected to the supply of fluid under pressure to the brake cylinder will be under the control of the smallest flexible diaphragm I8, so that a light brake cylinder pressure is obtained for an given increase in the pressure of fluid in pipe I2 in the same manner as described in connection with the operation of the embodiment shown in Fig. 1 of the drawings.

Since a release of the brakes following an application on an empty vehicle equipped with the variable load mechanism shown in Fig. l is accomplished in substantially the same manner as hereinbefore'described in connection withthe "operation of the equipment shown in Fig. 1 it is deemed unnecessary to repeat the description of of this operation here.

When the vehicle is brought to a stop and one or more of the vehicle doors are opened the circuit of the electromagnet 229 will be closed by the switches SI associated with the doors 92 as shown in dotted lines in Fig. 1. The energization of magnet 22!? seats valve 2 ii and unseats valve 2I6. With the valve 236 unseated fluid under pressure in chamber 285 and passage 2&7 connected to the piston chamber 235 will be vented to the atmosphere by way of passage 28B, chamber Iilfl in the magnet valve device 2 i 5, past unseated valve 2% and through atmospheric exhaust passage 22. The reduction offiuid pressure in chamber 236 due to such venting, permits the spring 235 to force the piston 234 upwardly drawing the teeth of the pawl 233 out of locking engagement with the teeth 232 of the ratchet bar 23 I The reduction of fluid pressure in chamber 205 permits the higher pressure acting in chamber 233 to move the piston 28! upwardly against the opposing pressure of the spring 288 until the piston. engages a sealing gasket 2'58. When the piston 25!! has been thus moved to its upper position the slide valve 284 will have been moved to a position in which the passage L -ii is connected to chamber .263. With passage 2) connected to chamber 2523 fluid under pressure in supply reservoir 4 flows to the chamber 255 in the fluid pressure motor I54, by way of pipe 78, chamber 22! in the magnet valve device 2 l5, passage 2%, chamber 253 in the valve portion E52 of the regulating valve device I5I, passage 2Ill and pipe 2! I.

Fluid under pressure supplied to chamber 255 causes the piston 255 and attached push rod 213 to move upwardly against the opposing pressure of spring 2'12. The push rod as it thus moves engages the end of the bar It will here. be understood that since the vehicle is empty the piston 265 will have made its full traverse atthe time the push rod engages with the bar 263 so that even though the locking pawl 233 is in its unlocked position, the bell crank lever and operating bar 2 56 will not be caused to move from their empty position inwhich they are shown.

Now as the vehicle is loaded the vehicle body will move downwardly, due to the compression of the body supporting sprin s by the increasing load, relative to the push rod 213. The bar 263,

since it is carried by the vehicle body and :is in' operative engagement with end of the push rod 213 of the fluid pressure motor I54 located on the truck, is caused to move upwardly in response to the downward movement of the vehicle body. The bar 263 as it thus moves causes the gear 26I to rotate in a counter-clockwise direction. The gear 28I as it is thus rotated causes the bar 258 to move longitudinally in the direction toward the left hand, the bar as it moves pulling the rod 251 in the same direction. Movement of the rod 251 in a direction toward the left hand causes the lever 253 to rock in a clockwise direction about the pivot pin 255.

The lever 253 as it is thus rocked causes the extension 25I and consequently the bar 245 to move in a direction toward the right hand against'the opposing pressure of the spring 252. As the bar 246 is moved in this direction, the cam surface 245 thereof which engages the roller 229 causes the bell crank lever 225 to rock in a clockwise di rection about the pivot pin 228 against the opposing pressure of the spring 244. This clockwise rotary motion of the bell crank lever 225 will continue as long as the load on the vehicle is being increased.

The bell crank lever 225, as it rocks in response to the increasing load on the vehicle, pulls the ratchet bar 23I longitudinally and at the same time moves the contact bar 231 clockwise to one or other of its three load positions depending upon the degree of increase of the load.

When the vehicle has been loaded, the vehicle doors are closed, the doors as they move from their open position, opening the circuit through the electro-magnet 220 as before described, thus effecting the deenergization of electro-magnet 220. With the electro-magnet 220 deenergized, the spring 2I9 acts to unseat the valve 2H and seat the valve 2I6. With the valve 2" unseated fluid under pressure from the supply reservoir 4 is again supplied to the chamber 205 and 236 throughthe circuit hereinbefore traced. When the pressure of fluid in chamber 236 has been increased to a degree sufiicient to overcome the opposing pressure of the spring 235, the piston is moved downwardly causing the teeth of the pawl 233 to engage the teeth of the ratchet bar 23I, thus locking the ratchet bar and attached bell crank lever 225 and consequently the contact bar 231 in the proper adjusted position.

When the combined pressure of fluid in chamber 205 and spring 208 acting on piston 29I has been increased to a degree sufficient to overcome the opposing pressure acting in chamber 203 the piston 20I and attached slide valve 204 will be moved to the position in which they are shown. With the slide valve thus positioned the fluid pressure in chamber 266 of the fluid pressure motor I54 will be vented to the atmosphere through the circuit previously described. The reduction of the pressure of fluid in chamber 266 due to such venting permits the spring 212 to force the piston 265 and attached push rod 213 to its extreme downward position, so that the end of the push rod 213 is moved out of engagement with the bar 253, for the purpose hereinbefore described.

As above mentioned the contact bar 231 will be positioned according to the load on the vehicle. If the vehicle is fully loaded the contact bar 231 will assume its full load position in which it will connect the contact member I58 to the contact fingers 238, 239, and 240. If the ve hicle is only lightly loaded the contact bar will be positioned so that it connects the contact member I58 to the contact fingers 238 only, and if the vehicle is more heavily loaded, but not fully loaded, the contact bar will connect the contact member I98 to the contact fingers 238 and 239 the contact fingers 240 remaining disconnected from the contact member I58.

When it is desired to effect an application of the brakes, fluid under pressure is supplied through pipe I2 and passage 32 to chamber 30 of the relay valve device I50 as hereinbefore described in connection with an application of the brakes on an empty vehicle. Fluid under pressure supplied to passage 32 flows by way of passage I10 to chambers I69, I18, and I88 of the magnet valves I51, I58, and I59, respectively. Fluid under pressure in passage I10 also flows by Way of connected passage 200 to chamber I99 of the fluid pressure operated switch device I9I, where at a low pressure piston I92 is actuated upwardly, against the bias of spring I98, to close contacts I95. With these contacts closed the positive terminal of battery I3 is connected by way of conductor I96, contacts I95, bridging member I94 and conductor I91 to contact member I98.

As above described the contact bar 251 will be positioned according to the load on the vehicle, thus if the vehicle is fully loaded the contact bar will connect contact member I98 to contact fingers 238, 239, and 240. Under these conditions the electro-magnets I68, I11, and I 81 of the magnet valves devices I 51, I58, and I59, respectively, will be energized. The circuit to the magnet I51 including contact member I98, contact bar 231, contact finger 238 conduit 24I, through the coil or winding of the electro-magnet I 58 to a ground connection 280. The circuit to the magnet I58 including contact member I98, contact bar 231, contact finger 239, conduit 242, through the coil or winding of the electro-magnet I11 to the ground connection 280. The circuit to the magnet I59 including contact member I98, contact bar 231, contact finger 239, conduit 243, through the coil or winding of the electromagnet I81 and a ground connection 28I.

With the electro-magnets I68, I11, and I81 energized, the valves I60, I14, and I84 of the magnet valve devices I 51, I 58, and I59, respectively, will be actuated to their unseated position. With these valves thus positioned communica- 1 tion is opened between passage 32 and each of the diaphragm chambers 28, 21 and 25 in the relay valve device I50.

From passage 32 fluid under pressure flows to passage I19 and from this passage it now flows to diaphragm chambers 28, 21, and 26, the flow to the chamber 28 being by way of chamber I99 in magnet valve I51, past unseated valve I68, cham-. ber I13 and passage I04; the flow to chamber 21 being by way of chamber I18 in magnet valve I58, unseated valve I14, chamber I and passage I 85; the flow to chamber 25 being by way of chamber I88 in'rnagnet valve I59, past unseated valve I88, chamber I99, and passage I06.

It will thus be seen that all of the chambers 29, 2?, 28, and 30 of the relay valve device I50 are charged with fluid under pressure from the passage 32and, consequently the relay Valve device will operate to effect a heavy application of the brakes in the same manner as previously cribed in connection with the equipment shown in Fig. 1 when the vehicle is fully loaded.

If the vehicle is empty the contact bar 231 of the switch portion I53 will be in the position in which it is shown in Fig. -2. so that the electroma gnets I58, III, and IE! will be maintained deenergized, thus when an application of the brakes is initiated the supply of fluid under pres ure to the brake cylinder will be under control of the smallest flexible diaphragm I8, thereby effectin a light brake cylinder pressure for any given increase in the pressure of fluid in pipe I2. It the vehicle is lightly loaded the contact bar 237 will be in the position in which it establishes contact between contact member I98 and contact finger 238, so that the .electro-magnet I68 of magnet valve device I51 will be energized. With this magnet energized the valve I60 therein will be unseated, thus establishing communication from the passage 32 to the passage 1 [l4 and consequently diaphragm chamber 28 through a circuit previously traced, so that the diaphragm I! which has a greater face area than the smallest diaphragm I8 act to control the valve mechanism to provide a higher brake cylinder pressure for a given increase in the pressure of fluid in pipe I2. If however, the vehicle is more heavily loaded the contact bar 231 will be in the position to establish contact between contact member I98 and the contact fingers 23B and 239, so that the electromagnets I68 and II! of magnet valve device I51 and I58, respectively, will be energized. With these electro-magnets energized the valves I60 and H4 will be unseated, thus establishing communication from the passage 32 to the passages I04 and I25 and consequently to the chambers 27 and 23, so that the diaphragm I6 which has a greater face area than the diaphragm I'I act to control the valve mechanism to provide a still higher brake cylinder pressure for any given. in crease in pressure of fluid in pipe I2.

In initiating the release of the brakes after an application effected on a fully loaded or a partially loaded vehicle, fluid under pressure in the pipe I2 is vented to the atmosphere as hereinbeiore described. In the event of a fully loaded vehicle fluid under pressure in chambers 26, 21, and 28, is vented to the passage 32 and connected pip I2 past the check valve 35, 35a and 3511, respectively. From chambers 25, 21, and 28 fluid under pressure also flows to passage 32 by way of the magnet valve device I51, I58, and I59. The flow from chamber 25 being by way of passage I06 and magnet valve device I55; the flow from chamber 2! being by way of passage I and magnet valve device I58; the flow from chamber 28 being by way of passage I04 and magnet valve device I5'I. The chamber 35, being directly connected to the passage 32 obviously reduces with the pressure in pipe I2 independently of th check valves and independently of the magnet valve devices.

When the vehicle is partially loaded the pressure in any of the chambers 21 and 2B which is charged with fluid under pressure is correspondingly released according to the reduction in pressure in pipe I2, by flow of fluid past the check valves 35a and 35b, respectively, and also by way of passages I35 and I04 and the magnet valves devices I58 and I51, respectively.

As before described, with these chambers vented, the relay valve device will operate to eiiect a release of the brakes.

Embodiment shown in Fig. 3

In Fig. 3 of the drawings another form of the invention is illustrated in which the control; of 76 aeaascs the supply of fluid under pressure to and the release of fluid under pressure from the relay valve device is accomplished through the medium of a slide valve operative according to variations in the weight of the load carried by the vehicle.

In this figure, the relay valve device illustrated in Fig. 2 has been modified by omitting the magnet valve casing I56 and thereby the control magnets I5'I, I58, and I59 and a cover plate 359 is substituted therefore. The regulating valve device differs from the corresponding device of the equipment shown in Fig. 2 in that the electrical contacts for controlling the magnet valve devices I51, I58, and I59 are omitted and a slide valve 3IJI substituted therefor. The slide valve 3II is operated by a ratchet bar 352 which bar is in some respects similar to the ratchet bar 23I shown in Fig. 2 of the drawings.

It will be understood that the fluid pressure motor I54 and associated parts used for positioning the regulating valve device although not shown in Fig. 3, will be identical with those shown in Fig. 2..

In this embodiment of the invention the passages I94, I05, and H16 leading to diaphragm chambers 28, 21, and 26, respectively, in the relay valve device are connected to pipes and passages 354, 355, 355, respectively, which lead to the seat for the slide valve 30 I.

The slide valve 30I is contained in a chamber 310 which is in constant open communication with the passage 32 by way of a passage 308. This slide valve is operatively connected by means of a pin 3| I to the ratchet bar 302, which bar is connected to one end of the link 235 which at its opposite end is connected to the ann 221 of the bell crank lever 225.

From the foregoing description of the operation of the variable load mechanism illustrated in Fig. .2 it will be understood that the regulating valve device illustrated in Fig. 3 is in its empty vehicle position. It will also be understood that when the vehicle doors are opened and the vehicle is being loaded the bell crank lever 225 is rocked in a clockwise direction about the pin 228, causing the ratchet bar 302 and consequently the slide valve 3IJI to move in a direction toward the right hand, and that this movement of the ratchet bar and slide valve will continue as long as the load on the vehicle is being increased until the vehicle is fully loaded. With this in mind it will be obvious that the slide valve 3M will be positional according to the load on the vehicle.

If the vehicle is empty the slide valve 35: will be in the position in which it is shown in Fig. 3, in which passage 32 is connected to the diaphragm chamber 30 only. If the vehicle is fully loaded the slide valve 35I will be moved to a position in which it uncovers the passages 304 355, and 3115 thereby connecting them to the chamber 3? and consequently to passage 32. If the vehicle is only lightly loaded the slide valve will be positioned to uncover only passage 354, and if the vehicle is more heavily loaded, but not fully loaded, the slide valve will be positioned to uncover passages 304and 395.

When it is desired to effect an application of the brakes, fluid under pressure is supplied to pipe I2 and passage 32 in the usual manner, and if the vehicle is empty, fluid under pressure in passage 32 flows only to chamber 38, thus the supply of fluid under pressure to the brake cylinder will be under control of the smallest diaphragm I3; and if the vehicle is lightly loaded, fluid under pressure in passage 32 flows to chamindependently of the slide valve I.

ber 30 and also to chamber 28 being by way of passage 308, chamber 3I0, passage and pipe 304 and passage I04, so that the supply of fluid/under pressure to the brake cylinder will be under control of the diaphragm II. If the vehicle is more heavily loaded, but not fully loaded, fluid under pressure in passage 32 flows to chamber 30 and in addition to chamber 28 and 21, the flow of fluid under pressure to chamber 21 being by way of passage 308, chamber 3I0, passage and pipe 305 and passage I05, so that the supply of fluid under pressure to the brake cylinder will be under control of the diaphragm I6. If however the vehicle is fully loaded fluid under pressure in passage 32 flows to all of the diaphragm chambers 30, 28, 21, and 26, the flow to chamber 26 being by way of passage 308, chamber 3I0, passage and pipe 306 and passage I06, so that the supply of fluid under pressure to the brake cylinder will be under control of the diaphragm I5.

In initiating a release of the brakes after an application effected on a fully loaded vehicle or partially loaded vehicle, fluid under pressure in pipe I2 and connected passage 32 is vented to the atmosphere as previously described. In the event of a fully loaded vehicle fluid under pressure in chambers 26, 21, and 28, is vented to atmosphere past the check valves 35, 35a and 35b, respectively, and also by way of passages I06, I05, and I04 respectively, chamber 3I0, passage 308, passage 32 and pipe I2. The chamber 30, being directly connected to passage 32 thus reduces with the pressure in pipe I2 independently of the check valves 35, 35a and 35b.

When the vehicle is partially loaded the pressure in any of the chambers 21 and 26, which are charged with fluid under pressure, is correspondingly reduced according to the reduction in pressure in pipe I2, by flow of fluid past check valves 35a and 35b, respectively, chamber 3I0, passage 308, passage 32 and pipe I2. As before mentioned in connection with release on a fully loaded vehicle the pressure of fluid in chamber 30 reduces independently of the check valves and also If the release is initiated following an application on an empty vehicle the pressure of fluid in chamber 30 as just described reduces directly with the pressure in passage 32.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a variable load brake equipment for vehicles, in combination, a brake cylinder, brake control means operatively responsive to the pressure of fluid supplied thereto for controlling the degree of pressure in said brake cylinder, valve means having a plurality of different control positions and effective, dependent upon its position, to condition the brake control means dif ferently so as to establish different fluid pressures in the brake cylinder for the same pressure of fluid supplied to the brake control means, regulating means controlled according to the load on the vehicle for positioning said valve means in its appropriate control position, a door for the vehicle, and means operative upon the opening of said door for controlling the operation of said regulating means.

2. In a variable load brake equipment for vehicles, in combination, a brake cylinder, brake control means operatively responsive to the pressure of fluid supplied thereto for controlling the degree of pressure in said brake cylinder, valve means having a plurality of different control positions and effective, dependent upon its position, to condition the brake control means differently so as to establish different fluid pressures in the brake cylinder for the same pressure of fluid supplied to the brake control means, regulating means controlled according to the load on the vehicle for positioning said valve means in its appropriate control position, locking means for locking the regulating means in its adjusted position, a door for the vehicle, and means con trolled by the .operation of said door for controlling the operation of the locking means.

3. In a variable load brake equipment for vehicles, in combination a brake cylinder, brake control means operatively responsive to the pressure of fluid supplied thereto for controlling the degree of pressure in said brake cylinder, valve means having a plurality of different control positions and effective, dependent upon its posi-.

tion, to condition the brake control means differently so as to establish diiferent fluid pressures in the brake cylinder for the same pressure of fluid supplied to the brake control means, regulating means controlled according to the load on the vehicle for positioning said valve means in its appropriate control position, a door for the vehicle, electro-responsive means operative upon the closing of said door for maintaining said regulating means in its adjusted position.

4. In a variable load brake equipment for vehicles, in combination, a brake cylinder, brake control means operatively responsive to the pressure of fluid supplied thereto for controlling the degree of pressure in said brake cylinder, a slide valve effective, dependent upon its position, to condition the brake control means differently so as to establish different fluid pressures in the brake cylinder for the same pressure of fluid supplied to the brake control means, lever means,

for positioning said slide valve, a door for the vehicle, and means operative according to the load on the vehicle when the door is open for actuating the lever means.

5. In a variable load brake equipment for vehicles, in combination, a brake cylinder, brake control means operatively responsive to the pressure of fluid supplied thereto for controlling the degree of pressure in said brake cylinder, a slide valve effective, dependent upon its position, to condition the brake control means differently so as to establish different fluid pressures in the brake cylinder for the same pressure of fluid supplied to the brake control means, a door for the vehicle, and means operative upon theopen-' slide valve effective, dependent upon its position,

to condition the brake control means differently so as to establish different fluid pressures in the brake cylinder for the same pressure of fluid sup plied to the brake control means, a door for the vehicle, and means operative according to the load on the vehicle when the door is open for positioning said slide valve and operativeupon the closing of said door for causing said slide valve to be locked in its adjusted position.

7. In a variable load brake equipment for vehicles, in combination, a brake cylinder, brake control means operativelyresponsive to the pressureof fluid supplied thereto in controlling the degree of pressure in said brake cylinder, a slide valve effective, dependent upon its position, to condition the brake control means differently .so as to establish different fluid pressures in the brake cylinder for the same pressure of fluid supplied to the brake control means, a door for the vehicle, means operative according to the load on the vehicle when said door'is open for positioning said slide valve, a mechanism for looking said means in its adjusted position, said mechanism being operative upon the closing of said door for locking said means in its adjusted position and operative upon the opening of said door for unlocking said means.

8. In a variable load brake equipment for vehicles, in combination, a brake cylinder, brake control means operatively responsive to the pressure of fluid supplied thereto for controlling the degree of pressure in said brake cylinder, elec trical contact means eifective, dependent upon its position, to condition the brake control means differently so as to establish different fluid pressures in the brake cylinder for the same pressure of fluids supplied to the brake control means, lever means for positioning said contact means, a dOOr for the vehicle, and means operative according to the load on the vehicle when the door is open for actuating the lever means.

9. In a variable load brake equipment for vehicles, in combination, a brake cylinder, brake control means operatively responsive to the pressure of fluid supplied thereto for controlling the degree of pressure in said brak cylinder, electrical contact means effective, dependent upon its position, to condition the brake control means differently so as to establish different fluid pres sures in the brake cylinder for the same pressure of fluid supplied to the brake control means, means for actuating said contact means, a door for the vehicle, and means operative according to the load on the vehicle when the door is open for adjusting the actuating means, and means operative upon the closing of said door for maintaining said actuating means in its adjusted position.

10. In a variable load brake equipment for vehicles, in combination, a brake cylinder, 2. control pipe, brake control means operatively responsive to the pressure of fluid supplied to said control pipe for controlling the degree of pressure in said brake cylinder, said brake control means having a plurality of electroresponsive means effective, dependent upon which of the electroresponsive means are energized or deenergized to condition it differently so as to establish different fluid pressures in the brake cylinder for the same pressure of fluid supplied to said control pipe, contact means for controlling the energization and .deenergization of said electroresponsive means, a door for the vehicle, and regulating means operative upon the opening of said door and according to the load on the vehicle for positionin said contact means.

11. In a variable load brake equipment for vehicles, in combination, a brake cylinder, a control pipe, brake control means operatively responsive to the pressure of fluid supplied to said control pipe for controlling the degree of pressure in said brake cylinder, said brake control means having a pluralit of electroresponsive means effective, dependent upon which of the electroresponsive means are energized or deenergized to condition it difierently so as to establish different fluid pressures in the brake cylinder for the same pressure of fluid supplied to said control pipe, contact means for controlling the energization and deenergization of said electroresponsive means, a door for the vehicle, means operative according to the load on the vehicle when said door is open for positioning said contact means, a mechanism for locking said means in its adjusted position, said mechanism being operative upon the closing of said door for locking said means in its adjusted position and operative upon the opening of said door for unlocking said means.

12. In a variable load brake equipment for vehicle, in combination, a brake cylinder, a control pipe, brake control means operatively responsive to the pressur of fluid supplied to said control pipe for controlling the degree of pressure in said brake cylinder, said brake control means having a plurality of electroresponsive means effective, dependent upon which of the electroresponsive means are energized or deenergized to condition it differently so as to establish different fluid pressures in the brake cylinder for the same pressure of fluid supplied to said control pipe, regulating means controlled according to the load on the Vehicle for controlling the en-' ergization and deenergization of said electroresponsive means, a door for the vehicle, another electroresponsive means operative upon the closing of said door for maintaining said regulating means in its adjusted position.

13. In a variable load brake equipment for vehicles, in combination, a control pipe, means for supplying fluid under pressure to said control pipe, a, brake cylinder, brake control means operatively responsive to the pressure of fluid supplied to said control pipe for controlling the degree of pressure in said brake cylinder, valve means having a plurality of difierent control positions for controlling the brake control means to cause it to establish different degrees of pressure in the brake cylinder for the same pressure of fluid supplied to said control pipe, means controlled according to the load on the vehicle for positioning said valve means in one of its different control positions for correspondingly different loads on the vehicle, a locking mechanism for locking said means in its adjusted position, a device operative periodically to perform a necessary function on the vehicle, and means controlled by the operation of said device for controlling the operation of the locking mechanism.

14. In a variable load brake equipment for vehicles, in combination, a brake pipe, a control pipe, a control valve device for supplyin fluid under pressure to said control pipe in accordance with a reduction in pressure in said brake pipe, a brake cylinder, a relay valve device responsive to the pressure of fluid supplied to said control pipe for controlling the degree of pres-v sure in said brake cylinder, valve means having a plurality of different control positions and effective, dependent upon its position, to condition the relay valve device differentl so as to estab-.

lish different fluid pressures in the brake cylinder for the same pressureof fluid supplied to the control pipe, regulatin means controlled according to the load on the vehicle for positioning said valve means, in its appropriate control position,

electroresponsive means operative when energized for rendering said regulating means operative and operative when deenergized for rendering said regulating means inoperative, and a door for the vehicle said door being operative when open to effect energization or said electroresponsive means and operative when closed to effect deenergization of said electroresponsive means.

15. In a variable load brake equipment for vehicles, in combination, a brake cylinder, brake control mean having a plurality of chambers and operative according to Which chamber or chambers are charged with fluid to the same pressure for effecting corresponding different degrees of pressure in the brake cylinder, means controlled according to the load on the vehicle for selectively determining which chamber or chambers will be charged with fluid under pressure when initiating an application of the brakes, a door for the vehicle, and electroresponsive means operative upon the opening of said door for effecting operation of said means.

16. In a variable load brake equipment for vehicles, in combination, a brake cylinder, brake control means having a plurality of chambers and operative according to which chamber or chambers are charged with fluid to the same pressure for effecting corresponding different degrees of pressure in the brake cylinder, valve means for selectively determining which chamber or chambers will be charged with fluid under pressure when initiating an application of the brakes, a door for the vehicle, and means operapressure for effecting corresponding different degrees of pressure in the brake cylinder, valve means for selectively determining which chamber or chambers will be charged with fluid under pressure when initiating an application of the brakes, a door for the vehicle, and means operative according to the load on the vehicle when the door is open for adjusting said valve means and operative upon the closing of said door for causing said valve means to be locked in its adjusted position.

18. In a variable load brake equipment for vehicles, in combination, a brake cylinder, brake control means having a plurality of chambers and operative according to which chamber or chambers are charged with fluid to the same pressure for effecting corresponding different degrees of pressure in the brake cylinder, 2. plurality of electroresponsive means effective, dependent upon which of the electroresponsive means are energized or deenergized to determine which chamber or chambers will be charged with fluid under pressure when initiating an application of the brakes, and means controlled according to the load on the vehicle for controlling the energization and deenergization of said electroresponsive means.

19. In a variable load brake equipment for vehicles, in combination, a brake cylinder, brake control means having a plurality of chambers and operative according to which chamber or chambers are charged with fluid to the same pressure for effecting corresponding different degrees of pressure in the brake cylinder, a plurality of electroresponsive means effective, dependent upon which of the electroresponsive means are energized or deenergized. to determine which chamber or chambers will be charged with fluid under pressure when initiating an application of the brakes, contact means for controlling the energization and deenergization of said electroresponsive means, a door for the vehicle, and regulating means operative upon the opening of said door and according to the load on the vehicle for positioning said contact means.

20. In a variable load brake equipment for vehicles, in combination, a control pipe, means for supplying fluid under pressure to said control pipe to effect an application of the brakes, a brake cylinder, brake control means having a plurality of chambers and operative according to which chamber or chambers are charged with fluid under pressure for effecting corresponding different degrees of pressure in the brake cylinder under the influence of the same supply pressure, a slide valve for selectively determining which chamber or chambers will be charged with fluid under pressure from the control pipe when an application of the brakes is initiated, means adjusted according to the load on the vehicle for controlling said slide valve, a locking mechanism for locking said means in its adjusted position, a door for the vehicle, and electroresponsive means under the control of said door for controlling said locking means.

21. In a variable load brake equipment for vehicles, in combination, a primary control pipe chargeable with fluid under pressure to initiate an application of the'brakes, a secondary control pipe effective to control the degree of application of the brakes in accordance with the degree of fluid pressure established in the secondary control pipe, a valve mechanism for controlling the supply and release of fluid under pressure to and from said secondary control pipe, a differential fluid pressure operated means for operating the valve mechanism, comprising a plurality of abutments of different areas, respectively, and arranged in spaced coaxial relation with the abutments decreasing successively in area, and means controlled according to the load on the vehicle and effective upon the initiation of an application of the brakes for selectively subjecting different ones of said abutments to the unbalanced pressure of the primary control pipe pressure to vary the force urging the valve mechanism in a direction to supply fluid under pressure to the secondary control pipe, the outer face of the largest abutment being subject to the pressure of the secondary control pipe acting to oppose the force of the primary control pipe pressure on the abutments, the pressure established in the secondary control pipe by the valve mechanism being in substantially the same ratio to the pressure in the primary control pipe as the area of the abutment subject to the unbalanced primary control pipe pressure is to the area of the largest abutment.

22. In a variable load brake equipment for vehicles, in combination, a brake cylinder; a control pipe; brake control means comprising a plurality of movable abutments, of different areas respectively, disposed in spaced coaxial relation, each pair of successive abutments having a chamber therebetween, and valve means operated by said abutments responsively to variations in the pressure in said chamber for controlling the degree of pressure in said brake cylinder; means controlled according to the load on the vehicle for selectively determining which chamber or chambers will be connected to said control pipe and thus be charged with fluid under pressure when an application of the brakes is effected; a door for the vehicle, and a magnet valve device operative upon the opening of the door for effecting operation of said means.

23. In a variable load brake equipment for vehicles, in combination, a brake cylinder; 2: control pipe; brake control means comprising a plurality of movable abutments of different areas respectively, disposed in spaced coaxial relation, each pair of successive abutments having a chamber therebetween, and valve means operated by said abutments responsively to variations in the pressure in said chamber for controlling the degree of pressures in said brake cylinder; means controlled according to the load on the vehicle for selectively determining which chamber or chambers will be connected to said control pipe and thus be charged with fluid under pressure when an application of thebrakes is effected; locking means for locking the means controlled by the load on the vehicle in its adjusted position; a device operative periodically to perform a necessary function on the vehicle; and means controlled by the operation of said device for controlling the operation of said locking means.

2a. In a variable load brake equipment for vehicles, in combination, valve means operative to control the degree of application and release of the brakes, a plurality of movable abutments, said abutments being so arranged that one of said abutments is effective when subject on one side to fluid at a certain pressure for effecting operation of said valve means to effect a certain degree of application of the brakes, and another of said abutments is effective when subject on one side to fluid at said certain pressure while said one abutment is not subject on the said. one side thereof to fluid under pressure, for efiecting operation of said valve means to eifect a degree of application different from said certain degree, means controlled according to the load on the vehicle for selectively controlling the supply of fluid under pressure to said abutments, a device operative periodically to perform a necessary function on the vehicle, and means controlled as an incident to the operation of said device for controlling the operation of said means.

25. In a variable load brake equipment for vehicles, in combination valve means operative to control the degree of application and release of the brakes, said valve means comprising a plu-' rality of unconnected movable abutments, means cooperating With said movable abutments to form a plurality of pressure chambers associated with said abutments, each of said abutments being responsive to fluid pressure in a corresponding one of said chambers for actuating said valve means; means for selectively controlling the supply of fluid under pressure to said chambers; a lever mechanism adjustable according to the load on'the vehicle for positioning; said means, a door for the vehicle, and means operative upon the closing of said door for causing said lever mechanism to be locked in its adjusted position.

26. In a variable load brake equipment for vehicles, in combination, a valve device operative to control the degree of application and release of the brakes; said means" comprising a plurality of cooperating unconnected movable abutments of diiierent areas so arranged in spaced coaxial relation as to move individually and collectively; means for causing fluid under pressure to be supplied simultaneously to all of the spaces between the successive pairs of abutments, to effect operation of said valve device to establish a cer-' tain degree of braking force, or to a varying number less than all of the spaces, to'eflect operation of said valve device to establish a second certain degree of braking force less than the first said certain degree of braking force; a lever mechanism for controlling the operation of said means; a door for the vehicle, and means operative according to the load on the vehicle when the door is open for efiecting operation of the lever mechanism.

27. In a variable load brake equipment for vehicles of the type comprisinga vehicle or car truck and a vehicle or car body carried by said truck and which is constructed and arranged for vertical movement relative to the truck, in combination, a brake cylinder, brak control means operatively responsive to the pressure of fluid supplied thereto for controlling the degree of pressure in said brake cylinder; valve means having a plurality of different control positions; said valve means being effective, dependent upon its control position, to condition the brake con trol means differently so as to establish different fluid pressures in the brake cylinder for the same pressure of fluid supplied to the brake control means; regulating means for adjusting said valve means in any one of its plurality of different con-' trol positions comprising a lever operatively connected to said valve means, a piston operatively connected to said lever, a member movable with the car truck, a member movable with the car body and operatively connected to said lever and movable to engage said car truck member; looking means for locking the regulating means in its adjusted position; a door for the vehicle; and means operative upon the closing of said door for effecting operation of said locking means to maintain said regulating means in its adjusted position.

ELLIS E. HEWITT. 

